In a conventional optical scanner, the filter apparatus can have different structure.
One of conventional apparatus (referring to FIG. 1) composes of a filter frame (a), a stepping motor (not shown), two large gears (b), two pinions (c), (d). A guiding channel (not shown) is disposed on the base to hold filter frame (a) and allows it to move steadily thereon.
Filter frame (a) is controlled by a pinion (d), two large gears (b) and a pinion (c) attached on motor axle (e). It has the shortcoming of too complicated structure and not easy to assemble or dismantle. It requires a screw driver or other tools to remove or assemble the filter assembly.